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Re^3: List EXE_FILES installed by CPAN

by afoken (Chancellor)
on Jun 24, 2018 at 05:21 UTC ( #1217314=note: print w/replies, xml ) Need Help??


in reply to Re^2: List EXE_FILES installed by CPAN
in thread List EXE_FILES installed by CPAN

I'm kinda feeling this would be better in the Obfuscated Code section. :-/

I feel you. It was a struggle. Is there an easier way to list CPAN EXE_FILES?

Perl supports something new and weird, called a script. It's been around for just a few decades, so I understand you have never heard of it before. Essentially, you put your code into a text file instead of insisting to type half a kilobyte of code into the command line over and over again. Start the file with #! followed by the name of the interpreter, in your case /usr/bin/perl, followed by a newline. Put your code into the next lines. See also https://www.in-ulm.de/~mascheck/various/shebang/ and perlrun.

The following quote comes from about the same time:

"I don't comment my code because if it was hard to write, then it should also be hard to read."

Sounds familiar? Yes, disk space and memory once were a scare resource. The MUMPS people learned that the hard way, and so their code typically looks like this, even after more than half of a century has passed:

Q() N S,N,T,I,K,Q S I="K",S="11",K="l1",Q="R",T="K" I I=T D T Q:$Q Q Q T I I,S&K S S=S+K Q

(Source: Wikipedia)

Great news: We have increased disk space, memory and CPU power by several orders of magnitude since that dark age. You no longer have to fight for every byte. So feel free to add as much comments as you like, explaining whatever is not obvious in your code.

Oh, and by the way: Some clever people invented something called POD, a way to create nice-looking documentation from a few lines of text inserted into your perl code. Other people have copied and extended that idea for other languages, at least twice (Javadoc, Doxygen).


Well, actually, no REAL MUMPS programmer would ever use functions. "We have labels. We don't need no stinkin' functions." And the NEW command is something to avoid at all costs. "Adding scope to variables is for the weeks. We know our variables, and we know when we have to copy then to prevent overwriting." Plus, those lines are way too short. The first three lines should be combined into one. "Stuffing as much code into a line as possible makes the code run faster. The interpreter is line-based."

(And no, I did not make up these quotes. They are real, from a time when I had to write MUMPS code for a living - in THIS century.)

Alexander

--
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)

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Re^4: List EXE_FILES installed by CPAN
by usemodperl (Beadle) on Jun 24, 2018 at 08:45 UTC
    EDIT: This code is wrong, see OP for correct version! Sorry...

    It's much easier to develop one-liners on the command line because it can so rapidly scroll through history of revisions. I can get a few test runs deep into trouble fiddling around with it and get back to a working version by hitting the up arrow a few times. In many years I haven't found a more rapid, easier and fun way to explore and deploy the power of perl. After achieving my desire from the machine these mega one liners find themselves all sorts of places to extend the operating system with new commands and functions.

    The way I'm posting them, dense and without triggering code wrap, makes it easy for me (and hopefully you) to copy directly from the webpage, to paste in a console. So you click download and see this gigantic one-liner that you want as a script? It depends on your operating system but for this script on Linux/Mac it goes something like this:
    
    Control|Command + a to select all
    Control|Command + c to copy selected text
    In a terminal type: echo
    Type one space
    Control|Command + p to paste text
    Type: | perltidy -st >cpanexe; nano cpanexe
    
    
    Here's a handy blob of code to throw at a terminal that transforms itself into a proper script, saved to disk, opened in an editor. This can make any one liner into a script! Just echo a pasted one-liner to another one-liner via pipe and then pipe that to perltidy which you can direct to save a file and then open it in your favorite text editor:

    echo perl -le'chomp(@_=`perldoc -T perllocal`); # List EXE_FILES installed by CPAN $_=join"\n",@_;@_=split/\"Module\"\s/; @_=grep/EXE_FILES:\s[^"]+/,@_;for(@_){@x=split/\n/; @x=grep/EXE|0m/,@x;push@z,@x}s/^\s+\*\s+\"([^\"]+).?/$1/ for@z; @_=grep/EXE_FILES/,@z;@_=map{substr($_,11,length($_))}@_;undef@z; for(@_){if(/\s/){@x=split/\s/;push@z,$_ for@x}else{push@z,$_}} %_=map{s/^\S+\///;$_=>1}@z;print$_ for sort{lc($a)cmp lc($b)}keys%_'| perl -e'@_=<STDIN>;print qq~\#\!/usr/bin/perl\n\nuse strict;~.qq~ use warnings;\n\n@_;~'|perltidy -st >cpanexe;nano cpanexe
    Result:

    #!/usr/bin/perl -w use strict; use warnings; chomp( @_ = `perldoc -T perllocal` ); # List EXE_FILES installed by CPAN $_ = join "\n", @_; @_ = split /\"Module\"\s/; @_ = grep /EXE_FILES:\s[^"]+/, @_; for (@_) { @x = split /\n/; @x = grep /EXE|0m/, @x; push @z, @x; } s/^\s+\*\s+\"([^\"]+).?/$1/ for @z; @_ = grep /EXE_FILES/, @z; @_ = map { substr( $_, 11, length($_) ) } @_; undef @z; for (@_) { if (/\s/) { @x = split /\s/; push @z, $_ for @x } else { push @z, $_ } } %_ = map { s/^\S+\///; $_ => 1 } @z; print $_ for sort { lc($a) cmp lc($b) } keys %_;
    I don't see the problem with dense code. It makes sense to me because that's how it gets created at the command line. Perlmonks understand it just as well as their spoken language so i don't understand the criticism or why we're constantly hounded by the cult of whitespace. Learn how to use perltidy and the rest of your operating system to make it do what you want instead of complaining. It's much more productive! ☺

    This is a one-liner! A tidy 20 lines. It gets 29 things done with perl to do something impossible:

    
    chomp join split grep for split grep push s for 
    grep map substr length undef for if split push 
    for else push map s print for sort cmp keys
    
    


    STOP REINVENTING WHEELS, START BUILDING SPACE ROCKETS!CPAN 🐪
      "It's much easier to develop one-liners on the command line because it can so rapidly scroll through history of revisions."

      That's what a VCS (Version Control System) is for (eg: Git, SVN, Mercurial etc). The added benefit is being able to much more easily read your code (because it's in a script), and it provides permanent revision bouncing (and commit cherry-picking, tagging etc).

        I develop Perl with Komodo which uses PerlTidy to check syntax when typing each character and GitHub Desktop to admire the evolution of large brojects (cause i like that typo). But when I develop ideas at the speed of thought none of that otherwise wonderful stuff can keep up with me and the up arrow. Once 1 line grows to 3 or 5 and it finally works then I can:
        echo perl -le 'print"JaPH"'| perl -e '$_=<STDIN>;s/perl\s\-?[a-zA-Z]*\s*\W//s; print qq~\#\!/usr/bin/perl\n\nuse strict;\nuse warnings;\n\n$_;~'| perltidy -st > script; nano script
        perl -MO=Deparse -e 'I T T M W O D T I'
        STOP REINVENTING WHEELS, START BUILDING SPACE ROCKETS!CPAN 🐪
      It gets 29 things done with perl to do something impossible
      It's not impossible. You should look up what that word means.
      It's much easier to develop one-liners on the command line because it can so rapidly scroll through history of revisions. I can get a few test runs deep into trouble fiddling around with it and get back to a working version by hitting the up arrow a few times. In many years I haven't found a more rapid, easier and fun way to explore and deploy the power of perl.
      For you maybe, it sounds stupid and time consuming, and looks awful. Thanks for perpetuating the meme that perl looks like line noise
        It's not impossible. You should look up what that word means.

        AFAIK it was not possible on my computer to get a simple sorted list of executables installed in path by CPAN without writing something (like perldoc -uT perllocal |grep "EXE_FILES: [a-z]" |cut -c 14- |sed 's/>//' |sort). It is now possible to do that on my computer with perl and thanks to the generosity of perlmonks.org (and yours-truly ;) your computer can do this too, if you want it to! Hopefully I didn't reinvent some wheel but I could not find what I want like:
        
        cpanlist --exeonly --sortbyname --nopath --unique
        
        
        I'm still working on --showdesc and --showhelp like output, at the command line of course 💻

        For you maybe, it sounds stupid and time consuming, and looks awful. Thanks for perpetuating the meme that perl looks like line noise

        It's so much faster than dealing with scripts. The brevity of Perl represents one of the most intense achievements of information compression in the known universe! Perlmonks appreciate and celebrate that sort of thing, why don't you? Funny pictures with your-text-here notwithstanding... ☺

        STOP REINVENTING WHEELS, START BUILDING SPACE ROCKETS!CPAN 🐪

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